Hot melt composition

ABSTRACT

An objective of the present invention is to provide a hot melt composition having a high form maintaining property at a high temperature and being in excellent adhesion to a substrate and in disassembly. The present invention relates to a hot melt composition comprising: (A1) a styrene-ethylene-ethylene/propylene-styrene block copolymer (SEEPS) and (B1) a hydrocarbon-based oil having an aniline point of 135° C. or more.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a hot melt composition, particularly tothe hot melt composition which can prevent deformation of the adhesiveat a high temperature and can be easily removed when a lightingappliance is disassembled.

BACKGROUND OF THE INVENTION

A hot melt adhesive is used as a sealant for an automotive lightingappliance. The hot melt adhesive is required to have high sealingproperty to the automotive lighting appliance and to be removable fromthe lighting appliance in consideration of disassembly when the lightingappliance is repaired.

Conventionally, although moisture-curable hot melt adhesives have beenused as sealing agents for a lighting appliance, it has been difficultto disassemble a lens and a housing part of the lighting appliance usingthese moisture-curable hot melt adhesives and thus they have not beensuitable for recent LED type lighting appliance that requires internalrepairs. Thus, a hot melt adhesive containing a styrene-based blockcopolymer has been used as a sealing agent for a lighting appliance insome cases.

Patent Literature 1 discloses a hot melt adhesive composition containinga styrene-ethylene-ethylene/propylene-styrene block copolymer (SEEPS)and a styrene-ethylene/propylene-styrene block copolymer (SEPS) asthermoplastic block copolymers. Patent Literature 2 discloses a hot meltcomposition comprising a styrene-ethylene-ethylene/propylene-styreneblock copolymer (SEEPS) and a styrene-ethylene/butylene-styrene blockcopolymer (SEBS).

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Laid-Open No. 2011-190287

Patent Literature 2: Japanese Patent Laid-Open No. 2008-127473

SUMMARY OF THE INVENTION Technical Problem

However, the hot melt adhesive composition described in PatentLiterature 1 can not completely prevent deformation of the adhesive at ahigh temperature. The hot melt composition described in PatentLiterature 2 has low disassembly property after aging test and failed tocompletely prevent deformation of the adhesive at a high temperature.

Therefore, it has been urgent to develop a hot melt adhesive which canbe removed from a lighting appliance and is less deformed even at a hightemperature. Particularly in recent years, in consideration of long-termuse of the lighting appliance, a hot melt adhesive having small increasein adhesive strength with time and being easy to be removed from alighting appliance, even if used for a long time, has been stronglydesired.

Solution to Problem

As a result of extensive studies to solve the above problems, thepresent inventors have found that a hot melt composition comprising aspecific thermoplastic block copolymer and a hydrocarbon-based liquidsoftening agent having an aniline point of a high temperature is hard todeform at a high temperature, has sufficient adhesive strength to alighting appliance or the like, and is easy to be removed, and thus theyhave completed the present invention.

The present invention and preferred embodiment of the present inventionis as follows.

1. A hot melt composition comprising:

-   -   (A1) a styrene-ethylene-ethylene/propylene-styrene block        copolymer (SEEPS) and    -   (B1) a hydrocarbon-based oil having an aniline point of 135° C.        or more.

2. The hot melt composition according to the above item 1, furthercomprising (A2) a styrene-ethylene/propylene block copolymer (SEP).

3. The hot melt composition according to the above item 2, wherein acontent of the styrene-ethylene/propylene block copolymer (SEP) (A2)based on 100 parts by weight of thestyrene-ethylene-ethylene/propylene-styrene block copolymer (SEEPS) (A1)is 5 to 100 parts by weight.

4. The hot melt composition according to any one of the above items 1 to3, further comprising (C) a tackifier resin.

5. The hot melt composition according to the above item 4, the tackifierresin (C) comprises (C1) a tackifier resin having a softening point of120° C. or more.

6. The hot melt composition according to any one of the above items 1 to5, further comprising a carbonate component.

7. The hot melt composition according to any one of the above items 1 to6, further comprising an acrylic component.

8. A lighting appliance in which a lens part and a housing part arejoined with the hot melt composition according to any one of the aboveitems 1 to 7.

9. A vehicle comprising the lighting appliance according to the aboveitem 8.

Advantageous Effects of Invention

In the hot melt composition of the present invention, deformation hardlyoccurs and form maintaining property is high at a high temperature, andadhesion to a substrate is excellent. Moreover, it is possible todisassemble the lighting appliance and the like using the hot meltcomposition of the present invention.

In the present specification, “form maintaining property” is defined asdifficulty to deform a hot melt composition at a high temperature. Thatis, the hot melt composition with less deformation at a high temperatureis more excellent in form maintaining property.

DETAILED DESCRIPTION OF THE INVENTION Description of Embodiments

The present invention relates to a hot melt composition comprising (A) athermoplastic block copolymer which is a copolymer of a vinyl-basedaromatic hydrocarbon and a conjugated diene compound and (B) ahydrocarbon-based liquid softening agent. In the hot melt composition ofthe present invention, the thermoplastic block copolymer (A) which is acopolymer of a vinyl-based aromatic hydrocarbon and a conjugated dienecompound comprises (A1) a styrene-ethylene-ethylene/propylene-styreneblock copolymer (SEEPS), and the hydrocarbon-based liquid softeningagent (B) comprises (B1) a hydrocarbon-based oil having an aniline pointof 135° C. or more. Each component will be explained below.

<(A) Thermoplastic Block Copolymer Which is a Copolymer of a Vinyl-BasedAromatic Hydrocarbon and a Conjugated Diene Compound>

The thermoplastic block copolymer (A) which is a copolymer of avinyl-based aromatic hydrocarbon and a conjugated diene compound(hereinafter, simply described as “a thermoplastic block copolymer (A)”or “component (A)”) is a copolymer obtained by block copolmerization ofa vinyl-based aromatic hydrocarbon and a conjugated diene compound(including copolymers in which the copolymers are furthercopolymerized). The “thermoplastic block copolymer (A)” may be a blockcopolymer having a vinyl-based aromatic hydrocarbon block and aconjugated diene compound block (non-hydrogenated block copolymer), or ahydrogenated block copolymer in which the block copolymers arehydrogenated. The thermoplastic block copolymer (A) may be used alone orin combination of two or more.

Here, the “vinyl-based aromatic hydrocarbon” means an aromatichydrocarbon compound having a vinyl group, and specific examples thereofinclude styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene,1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene andvinylanthracene. Particularly, styrene is preferred. These vinyl-basedaromatic hydrocarbons may be used alone or in combination of two ormore.

The “conjugated diene compound” means a diolefin compound having atleast a pair of conjugated double bonds. Specific examples of the“conjugated diene compound” include 1,3-butadiene,2-methyl-1,3-butadiene (or isoprene), 2,3-dimethyl-1,3-butadiene,1,3-pentadiene and 1,3-hexadiene. 1,3-butadiene and2-methyl-1,3-butadiene are particularly preferred. These conjugateddiene compounds may be used alone or in combination of two of more.

As the “non-hydrogenated block copolymer”, specific examples includethose in which blocks based on the conjugated diene compounds are nothydrogenated. As the “hydrogenated block copolymer”, specific examplesinclude block copolymers in which all or a part of the blocks based onthe conjugated diene compounds are hydrogenated.

The hydrogenated ratio of the “hydrogenated block copolymer” isrepresented by the “hydrogenation ratio”. “Hydrogenation ratio” of the“hydrogenated block copolymer” refers to a ratio of double bondsconverted to saturated hydrocarbon bonds by hydrogenation based on thetotal aliphatic double bonds contained in the blocks based on theconjugated diene compounds. The “hydrogenation ratio” may be measured byan infrared spectrophotometer, a nuclear magnetic resonance device andthe like. The hydrogenation ratio of thestyrene-ethylene-ethylene/propylene-styrene block copolymer (SEEPS) ispreferably 80% or more, and more preferably 90% or more.

The weight average molecular weight (Mw) of the thermoplastic blockcopolymer (A) is not particularly limited, but it is preferably from50,000 to 500,000, and more preferably 150,000 to 400,000. When theweight average molecular weight of the thermoplastic block copolymer (A)is within the above range, it is excellent in form maintaining property,shear adhesive strength and disassembly property. In the presentspecification, the weight average molecular weight and the numberaverage molecular weight are measured by gel permeation chromatography(GPC) using a calibration curve using monodisperse molecular weightpolystyrene as a standard substance to convert molecular weight.

A styrene content of the thermoplastic block copolymer (A) is notparticularly limited, but it is preferably 5 to 50 wt %, and morepreferably 10 to 40 wt %. The styrene content refers to the ratio ofstyrene block contained in the thermoplastic block copolymer (A). Whenthe styrene content of the thermoplastic block copolymer is within theabove range, the hot melt composition is excellent in heat resistance.

In the hot melt composition of the present invention, the thermoplasticblock copolymer (A) comprises “(A1) astyrene-ethylene-ethylene/propylene-styrene block copolymer (SEEPS)”,which is a hydrogenated block copolymer. Thestyrene-ethylene-ethylene/propylene-styrene block copolymer (SEEPS) (A1)is a hydrogenated product of a block copolymer composed of astyrene-butadiene-isoprene-styrene.

The SEEPS (A1) is swollen with a liquid softening agent such as processoil, imparts rubber elasticity to the hot melt composition, and canexhibit high heat-resistance, adhesion and strength as a sealing agent.During application of the hot melt composition, SEEPS exhibits fluidityas a thermoplastic resin by heating. Examples of commercial products ofSEEPS include SEPTON 4033, SEPTON 4044, SEPTON 4055, SEPTON 4077 andSEPTON 4099 manufactured by Kuraray Co., Ltd.

In the hot melt composition of the present invention, the thermoplasticblock copolymer (A) preferably comprises, in addition to the SEEPS (A1),“(A2) a styrene-ethylene/propylene block copolymer (SEP)” which isanother hydrogenated block copolymer.

The styrene-ethylene/propylene block copolymer (SEP) (A2) is ahydrogenated product of a block copolymer composed of styrene-isoprene.Since SEP is an A-B type hydrogenated block copolymer, the styrene blockis present only at one terminal end and the conjugated diene compound ispresent at the other terminal end. The presence of the conjugated dienecompound at the terminal end improves compatibility with a paraffinicprocess oil and makes it possible to impart a tack to the hot meltcomposition.

In the styrene-ethylene/propylene block copolymer (SEP)(A2), a styreneblock, which is a block part of an aromatic vinyl compound, can adheretightly to PC (polycarbonate), and an ethylene/propylene block, which isa block part of conjugated diene compounds, can adhere tightly to PP(polypropylene). Therefore, the SEP (A2) can contribute particularly tothe stabilization of the adhesion strength between two plastic adherendshaving different polarities. Examples of the commercial products of SEPinclude KRATON G1701, G1702HU manufactured by KRATON corporation andSEPTON 1001, SEPTON 1020 and the like manufactured by Kuraray Co., Ltd.

In the present invention, the content of the SEEPS (A1) to the totalamount of 100 parts by weight of the thermoplastic block copolymer (A)is preferably 20 parts by weight or more, more preferably 30 parts byweight or more, further preferably 50 parts by weight or more, stillfurther preferably 60 parts by weight or more and may be 100 parts byweight. The content of the component (A1) in the total amount of the hotmelt composition is preferably about 3 to 20 wt %.

When the thermoplastic block copolymer (A) comprises (A1) astyrene-ethylene-ethylene/propylene-styrene block copolymer (SEEPS) and(A2) a styrene-ethylene/propylene block copolymer (SEP), the blendingamount of SEP (A2) is preferably 5 to 100 parts by weight, morepreferably 10 to 80 parts by weight, further preferably 30 to 70 partsby weight, based on 100 parts by weight of the SEEPS (A1). When theblending amount of the styrene-ethylene/propylene block copolymer (SEP)(A2) is within the above range, the hot melt composition is hard todeform at a high temperature, excellent in adhesion to the lightingappliance, and easy to be removed, furthermore, fogging resistance isimproved and the lens can be prevented from being fogged.

In the present invention, the thermoplastic block copolymer (A) maycontain other block copolymers (A3) within a range not adverselyaffecting the present invention. Examples of other block copolymers (A3)include hydrogenated block copolymers other than (A1) SEEPS and (A2) SEPand non-hydrogenated block copolymers. Examples of the hydrogenatedproduct of the thermoplastic block copolymer include astyrene-ethylene/propylene-styrene block copolymer (also referred to as“SEPS”) in which a styrene-isoprene-styrene block copolymer ishydrogenated, a styrene-ethylene/butylene-styrene copolymer (alsoreferred to as “SEBS”) in which a styrene-butadiene-styrene blockcopolymer is hydrogenated. Examples of the non-hydrogenated blockcopolymer include styrene-isoprene-styrene block copolymer (alsoreferred to as “SIS”) and styrene-butadiene-styrene block copolymer(also referred to as “SBS”).

The content of the thermoplastic block copolymer (A) based on the totalamount of the hot melt composition is preferably 3 wt % or more, morepreferably from 4 wt % to 20 wt %, and further preferably from 4 wt % to10 wt %. When the content of the thermoplastic block copolymer (A) is 3wt % or more, the hot melt composition is excellent in heat resistance,adhesion and strength. When the content is 20 wt % or less, the shearadhesive strength of the hot melt composition does not becomeexcessively high and disassembly is easy.

<(B) Hydrocarbon-Based Liquid Softening Agent>

(B) a hydrocarbon-based liquid softening agent (also referred to simplyas “component (B)”) is blended for the purpose of adjusting the meltviscosity of the hot melt composition, imparting flexibility andimproving wettability to the adherend. The hydrocarbon-based liquidsoftening agent is mainly composed of carbon and hydrogen, and is in aliquid state at a room temperature (about 20° C.). The hydrocarbon-basedliquid softening agent may have hetero atoms such as an oxygen atom, anitrogen atom and a sulfur atom. Examples of the hydrocarbon-basedliquid softening agent include paraffinic, naphthenic or aromatic-basedprocess oil, liquid resins such as liquid polybutene, liquidpolybutadiene and liquid polyisoprene, liquid paraffin and olefinprocess oil. Examples of commercial products of the process oil includeDiana Process Oil manufactured by Idemitsu Kosan Co., Ltd.

In the present invention, the hydrocarbon-based liquid softening agent(B) comprises “(B1) a hydrocarbon-based oil having an aniline point of135° C. or more” (also simply referred to as “component (B1)”). Sincethe aniline point of the component (B1) is higher than aniline points ofthe oils generally used in ordinary hot melt compositions, the meltviscosity of the hot melt composition is increased. As a result, the hotmelt composition of the present invention can maintain its form at ahigh temperature, deformation is suppressed, and excellent formmaintaining property can be achieved. The upper limit of the anilinepoint of the hydrocarbon-based oil of component (B1) is not particularlylimited, but it is preferably 170° C. or less.

In the present specification, the aniline point is defined as the lowesttemperature at which equal volumes of aniline and a sample are uniformlypresent as a solution thereof, which is determined by a test method suchas a test tube method, a U-tube method, a thin film method, as describedin JIS 2256, K 2520. The temperature is increased while the mixture ofaniline and the sample are stirred to form a uniform and transparentsolution. Subsequently, from the state of uniform and transparentsolution, the temperature is lowered and then, the temperature at whichturbidity begins is measured. The aniline point is related to the rubberswellability of lubricating oil and process oil. The lower the anilinepoint of an oil is, the higher the solubility of the oil is.

Since the hydrocarbon-based oil of the component (B1) of the presentinvention has a high aniline point of 135° C. or more and a highmolecular weight, it's volatility is low and affinity with a midblockpart of the thermoplastic block copolymer (a block part based on aconjugated diene compound) is high.

When the lighting appliance sealed with a conventional hot melt adhesiveis used for a long time, there has been a problem that an adhesionstrength has become high due to volatilization of the oil in thecomposition and the like and thus disassembly property deteriorates. Onthe other hand, in the hot melt composition of the present invention,since the component (B1) continues to permeate into the midblock part ofthe thermoplastic block copolymer (A), the adhesive strength of the hotmelt composition does not continue to increase with time and thus stabledisassembly property can be maintained even when used for a long time.

In the hot melt composition of the present invention comprising thethermoplastic block copolymer (A) and the oil (B1) having an anilinepoint of 135° C. or more, since the component (B1) has a high molecularweight, the viscosity of the hot melt composition can be increased andform maintaining property can be enhanced.

As described above, since the hot melt composition of the presentinvention comprises the hydrocarbon-based oil (B1) having an anilinepoint of 135° C. or more, it is particularly suitable for sealingmaterials for a lighting appliance of an automobile and the like and itis excellent in disassembly property when the lighting appliance isrepaired. Further, it is possible to achieve long-term stable physicalproperties, and to achieve both of coating property and high formmaintaining property. Thus, excellent performance can be exhibited.

Examples of the hydrocarbon-based oil (B1) having an aniline point of135° C. or more include a process oil such as a paraffin oil derivedfrom a paraffinic crude oil, an aromatic oil and a naphthene oil derivedfrom a naphthenic crude oil, which have aniline points of 135° C. ormore. Commercial products thereof include Diana Process Oil PW-380. Asthe component (B1), one type may be used alone or two or more types maybe used in combination.

The hydrocarbon-based liquid softening agent (B) may comprise (B2) otherhydrocarbon-based liquid softening agents (also referred to as“component (B2)”) in addition to the hydrocarbon-based oil (B1) havingan aniline point of 135° C. or more.

In the hot melt composition of the present invention, the content of thecomponent (B1) based on 100 parts by weight of the component (B) ispreferably 30 parts by weight or more, more preferably 50 parts byweight or more, further preferably 60 parts by weight or more, and maybe 100 parts by weight. The content of the component (B1) in the totalamount of the hot melt composition is preferably about from 10 wt % to70 wt %.

The aniline point of other hydrocarbon-based liquid softening agents(B2) is preferably less than 135° C., more preferably 130° C. or less,and the lower limit is not particularly limited but is preferably 100°C. or more. Further, component (B2) is preferably a hydrocarbon-basedoil.

In one embodiment of the present invention, it is preferable that thehot melt composition comprises both of the component (B1) and thecomponent (B2) because the composition having a relatively low viscosityand high coating property can be obtained.

The content of the hydrocarbon-based liquid softening agent (B) in thetotal amount of the hot melt composition is preferably 30 wt % or more,more preferably 40 to 80 wt %, and further preferably 40 to 70 wt %.When the content of the component (B) is 30 wt % or more, the hot meltcomposition is excellent in form maintaining property at a hightemperature and disassembly property is excellent even after long-termuse. When the content is 80 wt % or less, suitable form maintainingproperty of the hot melt composition can be obtained.

<(C) Tackifier Resin>

One embodiment of the hot melt composition of the present inventionpreferably further comprises (C) a tackifier resin (also referred to as“component (C)”). Component (C) preferably comprises “(C1) a tackifierresin having a softening point of 120° C. or more”. Here, in the presentspecification, the softening point is a value measured by an automaticsoftening point apparatus (ring and ball type) according to thepetroleum asphalt test based on JIS K 2207. When the softening point ofthe tackifier resin is within the above range, the fluidity of thepolymer composition of the present invention is stabilized.

The content of the tackifier resin (C1) having a softening point of 120°C. or more based on 100 parts by weight of the component (C) ispreferably 50 parts by weight or more, more preferably 80 parts byweight or more, and may be 100 parts by weight. When the hot meltcomposition of the present invention comprises the tackifier resin (C1)having a softening point of 120° C. or more, higher form maintainingproperty can be kept.

The tackifier resin is not particularly limited, but examples thereofinclude a rosin resin, a terpene resin, a terpene phenol resin, anaromatic hydrocarbon modified terpene resin, a petroleum resin, aphenolic resin, an acrylic resin, a styrene-acrylic copolymer resin.From the viewpoint of adhesion, it is preferable that styrene-basedtackifier resin is basically used with aromatic hydrocarbon-basedterpene resin. Examples of commercial product thereof include Easttackseries and Endex series manufactured by Eastman Corporation.

The tackifier resin (C) may be used alone or in combination of two ormore.

The content of the tackifyier resin (C) based on the total amount of thehot melt composition may be 0 wt %, but it is preferably 20 wt % ormore, more preferably 30 to 50 wt %, further preferably 30 to 40 wt %.When the content of the component (C) is 20 wt % or more, the adhesivestrength of the hot melt composition is increased. When the content is50 wt % or less, excellent disassembly property of the hot meltcomposition can be easily obtained.

<Polycarbonate Component>

One embodiment of the hot melt composition of the present inventionpreferably further comprises a polycarbonate component. In the casewhere the adherend is a polycarbonate substrate, adhesiveness to thelens part of the lighting appliance is enhanced by chemical affinitybetween the polycarbonate component and the adherend. That is, when thehot melt composition comprises the polycarbonate component, highadhesion to the polycarbonate can be obtained. In the case of using thehot melt composition in the lighting appliance, when adhesion to apolycarbonate substrate is high, the hot melt composition can beremained on the lens (polycarbonate) side when the light appliance isdisassembled.

The polycarbonate component may be any polymer containing apolycarbonate structure. The polycarbonate component may have a terminalOH group, and may be a polycarbonate diol having OH groups at bothterminals. From the viewpoint of compatibility with the hot meltcomposition, a polycarbonate diol is preferred.

The number average molecular weight (Mn) of the polycarbonate componentis not particularly limited, but is preferably from 300 to 50,000, morepreferably from 500 to 40,000, further preferably from 1,000 to 35,000.

When a polycarbonate diol having a relatively small molecular weight(for example, Mn is 5000 or less) as a liquid component is used, thewettability to the polycarbonate (PC) is improved and a higher adhesioneffect can be obtained at the interface with the polycarbonatesubstrate. Examples of commercially available products of thepolycarbonate component include DURANOL T4672, T5650J and T5652manufactured by Asahi Kasei Chemicals Corporation, NIPPOLAN 982Rmanufactured by Nippon Polyurethane Industry Co., Ltd. and recycling PCmanufactured by Kansai Chemicals Co., Ltd.

The content of the polycarbonate component to the total amount of thehot melt composition may be 0 wt %, but it is preferably 3 to 15 wt %,and more preferably 4 to 10 wt %.

<Acrylic Component>

One embodiment of the hot melt composition of the present inventionpreferably further comprises an acrylic component. Since the solubilityparameter of the acrylic component is close to that of the polycarbonatewhich is a component of the lens of the lighting appliance, the adhesionof the hot melt composition to the polycarbonate is enhanced by thechemical affinity between the acrylic component and the polycarbonate.

Examples of the acrylic component include acrylic resins which arehomopolymers or copolymers of one or more compounds selected from ethylacrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexylmethacrylate, isononyl acrylate, methyl methacrylate, n-butylmethacrylate, methyl acrylate, acrylic acid, acrylamide, acrylonitrile,glycidyl methacrylate and the like. The acrylic copolymer may furthercomprise a monomer unit based on styrene, vinyl acetate or the like. Theacrylic component may have a low glass transition point or a high glasstransition point.

In one embodiment of the present invention, an acrylic resin in beadform having sharp molecular weight distribution are preferred becausethe hot melt composition containing this has excellent adhesion to thepolycarbonate resin and has excellent form maintaining property at ahigh temperature due to the acrylic resin having a high glass transitiontemperature.

Examples of commercially available products of the acrylic componentinclude Dianal series manufactured by Mitsubishi Rayon Corporation.

The content of the acrylic component to the total amount of the hot meltcomposition may be 0 wt %, preferably 3 to 20 wt % and more preferably 4to 15 wt %.

The hot melt composition of the present invention may comprise additivescommonly used in hot melt compositions, and they are not particularlylimited as long as the hot melt composition targeted by the presentinvention can be obtained. As such an additive, for example, anantioxidant, a plasticizer, an ultraviolet absorber, a pigment, arheology control agent, wax and the like may be added.

Examples of the “antioxidant” include phenol-based antioxidants,phosphite-based antioxidants, thioether-based antioxidants andamine-based antioxidant.

Examples of the “plasticizer” include a phthalate ester-basedplasticizer, an alkylsulfonic acid-based plasticizer, an adipateester-based plasticizer, an acetate-based plasticizer, a phosphateester-based plasticizer and the like.

Examples of the “ultraviolet absorber” include benzotriazole, hinderedamine, benzoate, benzotriazole and the like.

Examples of the “pigment” include carbon black, titanium oxide and thelike.

Examples of the “rheology control agent” include fatty acid amide, fumedsilica and the like. Examples of commercial products of the fatty acidamide include A-S-A T-1700, A-S-A T-1800 and the like manufactured byItoh Oil Chemicals Co., Ltd.

Examples of the “wax” include waxes such as paraffin wax andmicrocrystalline wax.

The hot melt composition of the present invention is produced byblending the above-mentioned components in a predetermined ratio,blending various additives as necessary, and mixing with heating andmelting. Specifically, the above components were charged into amelt-mixing pot equipped with a stirrer and were mixed with heating toprepare the product.

The method of using the hot melt composition of the present invention isnot particularly limited. For example, the hot melt composition of thepresent invention is melted by heating to 180 to 215° C. and is appliedto an adherend (for example, a first member and/or a second member). Thematerial of the second member may be the same as or different from thatof the first member. A method may be exemplified in which the firstmember and the second member are joined to form a joined body when thehot melt composition is in a molten state, and then it is allowed tosolidify under room temperature (about 20° C. to 25° C.) condition. Whenthe hot melt composition of the present invention is applied to anadherend, various applicators may be used.

Examples of the adherend to which the composition of the presentinvention may be applied include plastics (for example, polyolefin suchas polypropylene; polycarbonate; acrylic resin; PET resin), wood,rubber, glass and metal. It is exemplified as a preferred embodiment touse for adhesion of polycarbonate resins or acrylic resins; or adhesionbetween polycarbonate resin or acrylic resin and polypropylene.

The hot melt composition of the present invention is also suitable forjoining two plastics of different polarity such as joining PP(polypropylene) and PC (polycarbonate).

The hot melt composition according to the present invention may be usedas industrial sealing agents such as for sealing electronic and electriccomponents, automobile components, vehicle components and the like, andit is preferably used for a lighting appliance.

One embodiment of the present invention relates to a lighting applianceproduced by using the above hot melt composition. Examples of thelighting appliance include lighting appliance for automotive lamps (forexample, headlamps, rear combination lamps and the like) and lightingappliance for two-wheeled vehicles (motorbikes and the like).

In the case of being used for an automotive lighting appliance, thecomposition of the present invention may be used for sealing (bonding)the lens and the housing of the automotive lighting appliance. When thehot melt composition of the present invention is used in an automotivelighting appliance, the materials of the lens and the housing are notparticularly limited. Examples of the material of the lens include atransparent resin such as polycarbonate, acrylic resin (PMMA: polymethylmethacrylate resin) and PET, glass, or the like. Examples of thematerial of the housing include polyolefin such as polypropylene. Sincethe lighting appliance of the present invention is manufactured by usingthe above hot melt composition, for example, the inspection time afterthe lens and the housing of the automotive lighting appliance areadhered is shortened and the lens is not fogged.

Further, the hot melt composition of the present invention may be usedfor joining waterproof packing parts of household appliances such aswashing machines, dryers and refrigerators.

The present invention also relates to a vehicle having a lightingappliance manufactured by using the above hot melt composition. Sincethe vehicle of the present invention has a lighting appliancemanufactured by using the hot melt composition, the lighting applianceis not peeled off by heat or impact and the lens is not fogged, therebyallowing for safer travelling. The vehicle according to the presentinvention is not particularly limited as long as it has the abovelighting appliance. Specific examples of the vehicle include vehiclesaccording to the Road Traffic Law such as railroad vehicles such as anelectric railcar, a railroad car and a train, military vehicles such asa tank and an armored car, motor vehicles, motor bicycles (motorcycles),buses, and streetcars.

EXAMPLES

Hereinafter, the present invention will be described with reference toExamples and Comparative Examples, but these examples are for describingthe present invention and do not limit the present invention at all.

The components used in the hot melt compositions of Examples andComparative Examples are described below.

(A) Thermoplastic Block Copolymer

-   -   (A1-1) SEEPS (manufactured by Kuraray Co., Ltd., trade name:        SEPTON 4055, styrene content: 30 wt %)    -   (A1-2) SEEPS (manufactured by Kuraray Co., Ltd., trade name:        SEPTON 4077, styrene content: 30 wt %)    -   (A1-3) SEEPS (manufactured by Kuraray Co., Ltd., trade name:        SEPTON 4099, styrene content: 30 wt %)    -   (A2) SEP (manufactured by Kraton corporation, trade name KRATON        G1702HU, styrene content: 28 wt %, diblock content: 100 wt %)    -   (A3) SEPS (manufactured by Kuraray Co., Ltd, trade name: SEPTON        2005, styrene content: 20 wt %)

(B) Hydrocarbon-Based Liquid Softening Agent

-   -   (B1-1) paraffinic process oil (manufactured by Idemitsu Kosan        Co., Ltd., trade name: Diana Process Oil PW380, aniline point:        142.7° C.)    -   (B1-2) paraffinic process oil (manufactured by Idemitsu Kosan        Co., Ltd., trade name: Diana Process Oil PS430, aniline point:        138° C.)    -   (B2-1) paraffinic process oil (manufactured by Idemitsu Kosan        Co., Ltd., trade name: Diana Process Oil PW90, aniline point:        124.8° C.)    -   (B2-2) paraffinic process oil (manufactured by KANEDA Co., Ltd.,        trade name: Haikoru K350, aniline point: 122.4° C.)    -   (B2-3) paraffinic process oil (manufactured by Exxon Mobil,        trade name: Primol N382, aniline point: 121.9° C.)

(C) Tackifier Resin

-   -   (C1) hydrogenated C5 resin (manufactured by Eastman Chemical        Company, product name: Easttack resin H142R, weight-average        molecular weight: 1030, softening point: 142° C.)    -   (C2) hydrogenated DCPD resin (manufactured by Exxon Mobil, trade        name: Escorez 5320, a softening point: 125° C.)    -   (C3) pure C9 monomer resin (manufactured by Eastman Chemical        Company, trade name: Endex 155, softening point: 152° C.)    -   (C4) aromatic hydrocarbon resin (manufactured by Mitsui        Chemicals, trade name: FMR150, softening point: 150° C.)    -   (C5) terpene phenol resin (manufactured by Arizona Chemical,        trade name: SILVERES TP2019, softening point: 125° C., hydroxyl        value: 80)

(D) Antioxidant

-   -   (D1) hindered phenol antioxidant (manufactured by BASF, trade        name: Irganox 1010)

(E) Carbonate Component

-   -   (E1) polycarbonate diol (manufactured by Asahi Kasei Chemicals        Corporation, trade name: DURANOL T5652, a hydroxyl value: 56,        number-average molecular weight: 2000)    -   (E2) recycled polycarbonate resin (manufactured by Kansai        Chemicals Co., Ltd, trade name: recycling PC)

(F) Acrylic Component

-   -   (F1) acrylic resin (manufactured by Mitsubishi Rayon Co., Ltd,        trade name: DIANAL BR87, weight-average molecular weight:        25,000, glass transition temperature: 105° C.)

These components were blended in the blending ratios shown in Tables 4to 6, and melt-kneaded for 4 hours under reduced pressure by a heatingkneader (TKV 0.5-1 type) manufactured by Toshin Co., Ltd. set at 200°C., to obtain hot melt compositions of Examples 1 to 17 and ComparativeExamples 1 to 10. All numerical units relating to the composition(blending) of the hot melt compositions described in Tables 4 to 6 areparts by weight.

For each hot melt composition, form maintaining property, meltviscosity, shear test, PC adhesion, initial disassembly property anddisassembly property after heat-resistant cycle test, and the foggingresistance were evaluated. The outline of each evaluation will bedescribed below. Evaluation results of each hot melt composition areshown in Tables 4 to 6.

<Form Maintaining Property>

In order to evaluate the form maintaining property of each hot meltcomposition, a hot melt composition was poured into a polypropylenegroove having a depth of 12 mm, a width of 7 mm and a length of 14 mmand left to stand in a dryer at 130° C. for 24 hours at an angle of 70°,and the moving distance of the lower tip of the hot melt composition(i.e. the distance flowed out from the state immediately after beingapplied) was measured. The evaluation criteria based on the movingdistance are shown below.

TABLE 1 Evaluation Criteria for form maintaining property at 130° C.Evaluation moving distance ∘∘ 0.0 mm ∘ more than 0.0 mm and less than5.0 mm × 5.0 mm or more

<Melt Viscosity>

For the melt viscosity, hot melt compositions were heated and melted,and viscosities in a molten state were measured at 210° C., 200° C.,190° C. and 180° C. respectively at a rotation speed of 1 rpm using arotational viscometer manufactured by Brookfield Corporation. Thespindle was attached to the viscometer, the spindle was rotated, and thelowest value after 30 minutes from the start of heating was measured.Rotor No. 27 was used as the spindle.

<Initial Evaluation (PC Adhesion and Disassembly Property by ShearTest)>

In order to evaluate adhesion and disassembly property to PC(polycarbonate) of each hot melt composition, two PC plates each havinga width of 25 mm, a length of 100 mm, and a thickness of 3 mm were used,and the hot melt composition melted at 190° C. was applied to the plate,to prepare a shear test piece having an adhesive layer having a width of25 mm and a length of 5 mm. The gap between two polycarbonate plates wasabout 2 mm.

The shear test piece was set on a tensile tester (Tensilon® 250 type)and subjected to a tensile test at a tension speed of 50 mm/min at atemperature of 23° C. (room temperature), and the maximum load wasmeasured. The maximum load (N) was defined as shear adhesion strength.When the maximum load was 2.0 N or more and 6.0 N or less, it was judgedthat both PC adhesion and disassembly were obtained, and when it wassmaller than 2.0 N, it was judged that adhesion was insufficient.

The initial disassembly property was determined by failure mode in ashear test. When the failure mode of the hot melt composition on thepolycarbonate plate was an interface failure (also referred to asadhesion failure/“AF”), no material remained on the adhesion surface andit was judged that disassembly was OK. When failure mode of the adhesiveon the polycarbonate plate was cohesive failure even partially (alsoreferred to as cohesive failure/“CF”), it was judged that there was aproblem with disassembly because the adhesive remains on thepolycarbonate at the time of being disassembled. The evaluation criteriaare shown in Table 2.

TABLE 2 Evaluation Criteria for shear test of PC/PC Eval- Shear adhesionstrength uation and Failure mode Characteristic ∘∘ 2. 0 to 6.0 [N] andAF Adhesion is sufficient and it is easy to disassemble. ∘ 6.0 [N] ormore and Adhesion is sufficient and it is 10. 0 [N] or less, and AFpossible to disassemble. × less than 2.0 [N] Adhesion is insufficient.more than 10. 0 [N] Strength is excessively large and it is difficult todisassemble. cohesive failure (CF) There is a problem with disassembly.

<Evaluation After Heat-Resistant Cycle Test (PC Adhesion and DisassemblyProperty by Shear Test)>

In the same way, in order to evaluate the adhesion to PC (polycarbonate)and disassembly of each hot melt composition, two PC plates each havinga width of 25 mm, a length of 100 mm, and a thickness of 3 mm were used,and the hot melt composition melted at 190° C. was applied, to prepare ashear test piece having an adhesive layer having a width of 25 mm and alength of 5 mm. The gap between two polycarbonate plates was about 2 mm.The shear test piece was set in a small environmental test machine(SH-241 model manufactured by ESPEC Corporation), and 1 cycle wasdefined that after 1 hour at 20° C., the temperature was raised for 1hour, subsequently kept at 85° C. for 1 h, and then the temperature waslowered for 1 hour. After 1,000 cycles, the shear test piece was takenout from the heat-resistant cycle oven. The shear test piece was set ona tensile tester (Tensilon® 250 type) and subjected to a tensile test ata tension speed of 50 mm/min to measure the maximum load. The maximumload (N) was defined as shear adhesion.

In the same way as the initial evaluation, when the maximum load was 2.0N or more and 6.0 N or less and the failure mode was AF, it was judgedthat both PC adhesion and disassembly were obtained, and when it wassmaller than 2.0 N, it was judged that adhesion was insufficient. Theevaluation criteria were the same as in Table 2.

As an index of the strength stability after the heat-resistant cycletest, the strength change ratio was calculated from the initial shearadhesion strength and the shear adhesion strength after theheat-resistant cycle test by the following formula. Strength changeratio (%)=100×(Shear adhesion after heat-resistant cycle test−Initialshear adhesion strength)/Initial shear adhesion strength

Disassembly property after heat-resistant cycle test was determined byfailure mode in a shear test in the same way as the initial evaluation.When the failure mode of the hot melt composition on the polycarbonateplate was an interface failure (adhesion failure/AF), no materialremained on the adhesion surface and it was judged that disassembly wasOK. When the failure mode was AF and the strength change ratio was 20%or less, it was judged that it can be disassembled after aheat-resistant cycle test or after a long-term test expected in actualvehicle use. When a failure mode of the adhesive on the polycarbonateplate was cohesive failure even partially (cohesive failure/CF), it wasjudged that there was a problem with disassembly because the adhesiveremains on the polycarbonate plate at the time of being disassembled.The evaluation criteria are shown in Table 3.

TABLE 3 Evaluation Criteria of disassembly after heat-resistant cycletest Eval- Strength change ratio and uation failure mode Characteristic∘∘ Strength change ratio is less It is easy to disassemble. than 10% andAF ∘ Strength change ratio is It is possible to disassemble. 10 to 20%and AF × Strength change ratio is more There is difficulty with than 20%or CF disassembly.

<Fogging Resistance Test>

The hot melt composition melted at 190° C. was placed in a cartridge andapplied to a release paper in a 2 mm bead shape using a hot melt gun(Heat Gun TR80 model manufactured by REKA Klebetechnik GmbH & Co. KG).The above adhesive was cut and 1 g of it was put into a 110 ml glassbottle (screw bottle No. 8 manufactured by AS ONE Co., Ltd. having aheight of 120 mm, a diameter of 21 mm, a center part outside diameter of40 mm), covered with a polycarbonate plate and a weight was placedthereon.

The glass bottle containing the adhesive, the polycarbonate plate andthe weight were placed in an oil bath (Heating Bath B-491 manufacturedby BUCHI Co., Ltd.). The silicone oil in the oil bath was heated, it wasconfirmed that the temperature reached 90° C., and heating was carriedout for 24 hours. After heating for 24 hours, the glass bottle, thepolycarbonate plate and the weight were taken out from the oil bath andleft to stand until room temperature was reached. Thereafter, the weightwas removed, and the deposit on the polycarbonate plate was observed.

(Evaluation Criteria for Fogging Resistance Test)

Evaluation criteria for fogging resistance test are as follows.

◯: No deposit was observed on the polycarbonate plate.

×: A deposit was observed on the polycarbonate plate.

TABLE 4 Composition Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 (A1-1) 3030 30 30 30 30 30 (A1-2) 70 70 70 70 70 70 70 (A2) 60 60 60 60 40 (A3)(B1-1) 1300 1300 1300 1300 500 900 900 (B2-1) 400 400 400 (C1) 360 360360 360 360 360 360 (C2) 340 340 340 340 340 340 340 (C3) 20 20 20 20 20(D1) 10 10 10 10 10 10 10 (E1) (E2) (F1) Total 2110 2130 2170 2190 17902190 2170 Form maintaining property at 130° C. ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ MeltViscosity [mPa · s] (210° C.) 82000 59500 246000 200000 53250 3775023500 Melt Viscosity [mPa · s] (200° C.) 215250 159750 250000 250000159750 117000 82500 or more or more Melt Viscosity [mPa · s] (190° C.)250000 250000 250000 250000 250000 250000 226250 or more or more or moreor more or more or more Melt Viscosity [mPa · s] (180° C.) 250000 250000250000 250000 250000 250000 250000 or more or more or more or more ormore or more or more Initial Evaluation of shear test ∘∘ ∘ ∘∘ ∘ ∘ ∘∘ ∘∘Evaluation for PC/PC Shear adhesion strength 4.9 8.0 6.0 6.4 6.6 4.4 2.9for PC/PC (room temperature)[N] Disassembly property AF AF AF AF AF AFAF (failure mode of shear test) Evaluation Evaluation of shear test ∘∘ ∘∘∘ ∘ ∘ ∘∘ ∘∘ after heat- for PC/PC resistant Shear adhesion strength 5.07.9 5.9 6.4 6.8 4.5 3.1 cycle test for PC/PC (room temperature)[N]Evaluation of ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ disassembly property afterheat-resistant cycle test Strength change ratio 2.7 −1.3 −1.7 0.0 3.02.3 6.9 after heat-resistant cycle test (%) disassembly property AF AFAF AF AF AF AF (failure mode of shear test) Fogging resistance test ∘ ∘∘ ∘ ∘ ∘ ∘ Ex. = Example

TABLE 5 Composition Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex.15 Ex. 16 Ex. 17 (A1-1) 30 30 30 30 30 30 30 50 30 30 (A1-2) 70 70 70 7070 70 70 50 70 70 (A2) 80 40 40 60 60 20 10 60 60 (A3) (B1-1) 900 700900 900 800 900 800 900 (B1-2) 1300 1300 (B2-1) 400 600 600 400 400 400400 400 (C1) 360 360 360 360 360 360 360 360 360 360 (C2) 340 340 340360 340 340 340 340 340 340 (C3) 20 20 20 20 20 20 20 20 20 (D1) 10 1010 10 10 10 10 10 10 10 (E1) 100 (E2) 100 (F1) 100 Total 2210 2170 23702190 2190 2250 2140 2190 2130 2190 Form maintaining property at 130° C.∘∘ ∘ ∘∘ ∘ ∘∘ ∘ ∘ ∘∘ ∘∘ ∘∘ Melt Viscosity [mPa · s] (210° C.) 53750 1650021000 46000 52500 6000 11500 24250 22750 37000 Melt Viscosity [mPa · s](200° C.) 150250 55250 77000 138000 152750 17750 39500 84750 75250108750 Melt Viscosity [mPa · s] (190° C.) 250000 165000 222250 250000250000 43500 60000 232750 220250 236250 or or or more more more MeltViscosity [mPa · s] (180° C.) 250000 236250 250000 250000 250000 102000220000 250000 250000 250000 or or or or or or or more more more moremore more more Initial Evaluation of shear test for PC/PC ∘∘ ∘ ∘∘ ∘∘ ∘∘∘∘ ∘∘ ∘∘ ∘∘ ∘∘ Evaluation Shear adhesion strength for PC/PC 2.9 8.0 2.93.3 4.0 4.0 4.5 4.4 2.0 4.4 (room temperature)[N] Disassembly propertyAF AF AF AF AF AF AF AF AF AF (failure mode of shear test) EvaluationEvaluation of shear test for PC/PC ∘∘ ∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ afterheat- Shear adhesion strength for PC/PC 3.4 7.8 2.9 3.5 4.2 4.0 4.5 4.32.1 4.5 resistant (room temperature)[N] cycle test Evaluation ofdisassembly property ∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ after heat-resistantcycle test Strength change ratio after 17.2 −2.5 0.0 6.1 5.0 0.0 0.0−2.3 5.0 2.3 heat-resistant cycle test (%) Disassembly property (failureAF AF AF AF AF AF AF AF AF AF mode of shear test) Fogging resistancetest ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ Ex. = Example

TABLE 6 Comp- Comp- Comp- Comp- Comp- Comp- Comp- Comp- Comp- Comp-Composition Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10(A1-1) 60 30 160 30 30 30 (A1-2) 100 70 70 70 70 200 (A1-3) 200 (A2) 6060 160 (A3) 60 160 (B1-1) 900 900 (B2-1) 900 900 900 900 900 400 400(B2-2) 2000 1300 (B2-3) 2000 (C1) 360 360 360 360 360 360 360 360 (C2)340 340 340 290 340 340 340 340 (C3) 20 20 20 70 20 20 20 (C4) 400 (C5)400 (D1) 10 10 10 10 10 10 10 10 10 10 Total 1790 1790 1790 1790 17902190 2190 2610 2110 2610 Form maintaining x x x x x x x x x x propertyat 130° C. Melt Viscosity [mPa · s] 1250 3000 1500 200 4000 2250 20008000 250 4250 (210° C.) Melt Viscosity [mPa · s] 3250 7500 4500 20011750 4500 4400 22500 500 11500 (200° C.) Melt Viscosity [mPa · s] 925020500 9000 250 39750 39000 38000 66000 1750 40500 (190° C.) MeltViscosity [mPa · s] 32750 64500 32750 350 139000 44250 42500 168750 6250128500 (180° C.) Initial Evaluation of shear x x ∘ x ∘ x x ∘ x xEvaluation test for PC/PC Shear adhesion 1.9 1.8 4.7 1.5 4.6 1.6 1.5 8.50.6 0.7 strength for PC/PC (room temperature)[N] Disassembly AF AF AF AFAF CF CF AF AF AF property (failure mode of shear test) EvaluationEvaluation of shear x x ∘ x ∘ x x ∘ x x after heat- test for PC/PCresistant Shear adhesion 2.9 3.0 10.2 2.0 5.7 2.0 2.1 10.3 0.7 0.8 cycletest strength for PC/PC (room temperature)[N] Evaluation of x x x x x xx x ∘ ∘ disassembly property after heat-resistant cycle test Strengthchange 52.6 66.7 117.0 33.3 23.9 25.0 40.0 21.2 16.7 14.3 ratio afterheat- resistant cycle test (%) Disassembly AF AF AF AF AF CF CF AF AF AFproperty (failure mode of shear test) Fogging resistance test x ∘ x x ∘∘ ∘ ∘ x ∘ Comp-Ex. = Comparative Example

As shown in Tables 4 and 5, for the hot melt compositions of theExamples, form maintaining property is very excellent and shear adhesionstrength was high, and thus it was possible to obtain high adhesion tocarbonate component. Further, for the hot melt compositions of theExamples, failure modes were AF and high disassembly property could beobtained.

In the hot melt compositions of the Examples, strength change ratio wassmall even after the heat-resistant cycle test and stable disassemblywas obtained. Accordingly, if the hot melt composition of the presentinvention is used for a lighting appliance, stable disassembly can beobtained after long-term use. Furthermore, the hot-melt compositions ofthe Examples had high fogging resistance and no fogging of the lens dueto heating occurred.

INDUSTRIAL APPLICABILITY

The present invention provides a hot melt composition used for bonding alens and a housing for automotive lighting appliance. For the hot meltcomposition according to the present invention, a sealing part can beeasily disassembled for replacement or maintenance of electricalcomponents in a lighting appliance represented by a light emittingdiode. In particular, the hot melt composition according to the presentinvention can satisfy high adhesion to a polycarbonate resin which isrequired for sealing applications, high disassemble property requiredfor repair and maintenance, and removing requirement from polycarbonatewhich is demand on workability at disassembling after even long-termuse.

1. A hot melt composition comprising: (A1) astyrene-ethylene-ethylene/propylene-styrene block copolymer (SEEPS) and(B1) a hydrocarbon-based oil having an aniline point of 135° C. or more.2. The hot melt composition according to claim 1, further comprising(A2) a styrene-ethylene/propylene block copolymer (SEP).
 3. The hot meltcomposition according to claim 2, wherein a content of thestyrene-ethylene/propylene block copolymer (SEP) (A2) based on 100 partsby weight of the styrene-ethylene-ethylene/propylene-styrene blockcopolymer (SEEPS) (A1) is 5 to 100 parts by weight.
 4. The hot meltcomposition according to claim 1, further comprising (C1) a tackifierresin having a softening point of 120° C. or more.
 5. A lightingappliance in which a lens part and a housing part are joined with thehot melt composition according to claim
 1. 6. A vehicle comprising thelighting appliance according to claim 5.